This application relates generally to aircraft capable of flight in both a rotary wing and fixed wing modes of flight and, more particularly, to apparatus for controlling the motion of the rotor/wing thereof.
Rotor/wing aircraft such as the aircraft disclosed in U.S. Pat. No. 5,454,530 titled "Canard Rotor/Wing" are capable of operation in both a helicopter and a fixed-wing mode of flight. In order to achieve this dual mode flight, a rotor/wing aircraft is equipped with a rotating hub, similar to the rotating hub of a helicopter, to which are attached a plurality of rotor blades extending radially outward from the hub. In the first flight regime the hub and rotor blades are rotated, in a manner similar to that of a helicopter. This enables the aircraft to move vertically, hover, and fly translationally at relatively slow speeds. In the second flight regime, the rotor is locked with the rotor blades positioned to operate as fixed wings, thereby enabling the aircraft to fly at relatively high speed configured as a conventional fixed-wing aircraft.
Historically a major obstacle to the practical implementation of rotor/wing aircraft has been the difficulties associated with transitioning between the two flight regimes, including the difficulties associated with stopping the rotating rotor blades quickly and indexing the blades precisely in position for fixed wing flight. Prior art apparatus for stopping and locking the rotor involved use of a spring-loaded shock absorber which decelerated the rotating hub during the initial stroke of the shock absorber and a rebound stop which locked the hub in position on the rebound stroke of the shock absorber. Disadvantages of the prior art approach include the size and weight of a shock absorber necessary to absorb the energy in the rotating hub and the impact loads imparted to the rotor/wing and other aircraft components.
Accordingly, what is needed is a compact, lightweight apparatus that quickly and efficiently decelerates and indexes a rotating rotor hub to an exact location without imparting unnecessary shock loads to the aircraft.